In recent years all-purpose liquid detergents have become widely accepted for cleaning hard surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs, linoleum or tile floors, washable wall paper, etc. Such all-purpose liquids comprise clear and opaque aqueous mixtures of water-soluble synthetic organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic phosphate builder salts was favored in the prior art all-purpose liquids. For example, such early phosphate-containing compositions are described in U.S. Pat. Nos. 2,560,839; 3,234,138; 3,350,319; and British Patent No.1,223,739.
Another approach to formulating hard surfaced or all-purpose liquid detergent composition where product homogeneity and clarity are important considerations involves the formation of oil-in-water (o/w) microemulsions which contain one or more surface-active detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent), water and a "cosurfactant" compound which provides product stability. By definition, an o/w microemulsion is a spontaneously forming colloidal dispersion of "oil" phase particles having a particle size in the range of 25 .ANG. to 800 .ANG. in a continuous aqueous phase.
In view of the extremely fine particle size of the dispersed oil phase particles, microemulsions are transparent to light and are clear and usually highly stable against phase separation.
Patent disclosures relating to use of grease-removal solvents in o/w microemulsions include, for example, European Patent Applications EP 0137615 and EP 0137616--Herbots et al; European Patent Application EP 0160762--Johnston et al; and U.S. Pat. No. 4,561,991--Herbots et al. Each of these patent disclosures also teaches using at least 5% by weight of grease-removal solvent.
However, since the amount of water immiscible and sparingly soluble components which can be present in an o/w microemulsion, with low total active ingredients without impairing the stability of the microemulsion is rather limited (for example, up to 18% by weight of the aqueous phase), the presence of such high quantities of grease-removal solvent tend to reduce the total amount of greasy or oily soils which can be taken up by and into the microemulsion without causing phase separation.
The following representative prior art patents also relate to liquid detergent cleaning compositions in the form of o/w microemulsions: U.S. Pat. Nos. 4,472,291--Rosario; 4,540,448--Gauteer et al; 3,723,330--Sheflin; etc.
Liquid detergent compositions which include terpenes, such as d-limonene, or other grease-removal solvent, although not disclosed to be in the form of o/w microemulsions, are the subject matter of the following representative patent documents: European Patent Application 0080749; British Patent Specification 1,603,047; U.S. Pat. Nos. 4,414,128; and 4,540,505. For example, U.S. Pat. No. 4,414,128 broadly discloses an aqueous liquid detergent composition characterized by, by weight:
(a) from 1% to 20% of a synthetic anionic, nonionic, amphoteric or zwitterionic surfactant or mixture thereof; PA1 (b) from 0.5% to 10% of a mono- or sesquiterpene or mixture thereof, at a weight ratio of (a):(b) lying in the range of 5:1 to 1:3; and PA1 (c ) from 0.5% 10% of a polar solvent having a solubility in water at 15.degree. C. in the range of from 0.2% to 10%. Other ingredients present in the formulations disclosed in this patent include from 0.05% to 2% by weight of an alkali metal, ammonium or alkanolammonium soap of a C.sub.13 -C.sub.24 fatty acid; a calcium sequestrant from 0.5% to 13% by weight; non-aqueous solvent, e.g., alcohols and glycol ethers, up to 10% by weight; and hydrotropes, e.g., urea, ethanolamines, salts of lower alkylaryl sulfonates, up to 10% by weight. All of the formulations shown in the Examples of this patent include relatively large amounts of detergent builder salts which are detrimental to surface shine and/or leave important residue after the product has been used/sprayed. PA1 1% to 10% of at least one surfactant selected from the group consisting of nonionic, and cationic surfactants and mixtures thereof; PA1 0 to 15% of a water-mixable cosurfactant having either limited ability or substantially no ability to dissolve oily or greasy soil; PA1 0 to 5%, more preferably 0.1% to 5% of a water insoluble hydrocarbon, essential oil or perfume; PA1 0 to 3%, more preferably 0.1% to 2% of piperonyl butoxide; PA1 0.025% to 1.5% of d-phenothrin; PA1 0 to 5.0% of at least one supplemental acaricidal agent; and PA1 the balance being water, wherein the composition does not contain a solid component having a mean particle size of 2 to 100 microns which would leave a pulverulent residue on the surface being treated or quartz, sand, siliceous earth, metal carbonate, SiO.sub.2, amorphous silica, silicates, polyacrylates or xanthan gum. Explicitly excluded from the instant compositions are anionic surfactants containing a sulfate, sulfonate or a carboxylate groups, alkanol amines, amines, phenol and phenolic compounds which do not have an ester group and N-lower alkyl neoalkanolamides such as methyl neodecamide and N,N-diethyl-meta-toluamide.
U.S. Pat. No. 5,082,584 discloses a microemulsion composition having an anionic surfactant, a cosurfactant, nonionic surfactant, perfume and water; however, these compositions do not contain acaricidal agents.
U.S. Pat. No. 4,666,940 discloses acaricidal agents in combination with solid components that leave a residue on the surface being treated.
One well known property of microemulsions is their behaviour to solubilize high amount of oil or non water soluble components. Active ingredients like pesticides, fungicides or acaricidal agents can be easily formulated in microemulsion compositions having low amount of surfactants. Those ingredients become also chemically more stable over time and their activity has been shown higher than when solubilized in a standard o/w or w/o emulsion.